a) Field of the Invention
The invention relates to a memory card structure, especially to a memory card of a circuit board replacing the lower case.
b) Description of the Prior Art
Traditional memory cards mainly consist of a case and a circuit board such as “Improved Structure of PC Memory Card Case” (Taiwan Utility Patent Publication No. 233068), “Integrated Refined Structure for Memory Card” (Taiwan Utility Patent Publication No. 481311), and a “New Structure for Memory Card Case” (Taiwan Utility Patent Publication No. 504063), etc. These previous patents merely illustrate different structure of the case by composing either an upper case and a lower case made of plastic materials, or an upper case and lower case made of a plastic frame combined with metal materials, or a metal board each disposed on both upper and lower side of the circuit board within a plastic case. However, the aforesaid still belong to a traditional structure of a case covering a circuit board. As shown on FIG. 1, the thickness t1 of a normal upper case 10 is about 1.1 mm the thickness t2 of the circuit board 20 is about 1 mm, and the thickness t3 of the lower case 30 is about 0.7 mm. Since the thickness of the traditional case structure cannot be shortened, the cost of materials cannot be decreased. Another serious defect is: due to the limited space of the case, the circuit board has to be made of special electronic parts, especially IC with bigger volume and in higher length, which also result in the cost not being decreased. Furthermore, the traditional way to make the contact terminal 21 on the circuit board 20, called “Gold Finger”, is limited to its space and thickness, which has to be produced by way of Wafer (Die), is considered as having much difficulty in technique, high rate of failure and time consuming in production.